<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>

    <!-- 
        typeof  检测6中属性值
        1 undefined
        2 number
        3 string 
        4 object   (null)
        5 boolean
        6 function   
        a++ 
        先自增 后赋值
        a++
        先赋值 后自增 
        + 运算符  
         其中一个数值类型为字符串 进行拼接 不进行算数运算
     -->


    <script src="./js/index1.js"></script>
    <script>
        
    </script>
</body>

</html>